1. Field of the Invention
The present invention relates to an image processing apparatus having a function of projecting the image of an original on a screen, like an overhead projector, and a function of forming an image of the original on a paper or a transparent sheet, like a copying machine.
2. Description of the Related Art
Conventional overhead projectors (hereinafter called "OHP") can be divided into two groups: transparence-type, and reflection-type.
In the transparence-type OHP, an original placed on a transparent support table is illuminated from the underside of the support table, and an image of the original is projected on a screen via a projector lens and a reflector mirror, both disposed above the support table.
In the reflection-type OHP, an original on a fresnel lens is illuminated from the upper side of the fresnel lens and a reflected image of the original is projected on the screen via a projector lens and a reflector mirror, both disposed above the fresnel lens.
Apart from a simple original that can be formed by manually drawing or writing a figure or a character directly on a transparent sheet with a pen, an ordinary original to be used in the OHP is formed by copying an image on a transparent sheet by using an electrophotographic copying machine, for example.
When giving a lecture, a presentation or a briefing by using an OHP at a school, a presentation site or a meeting room, it is necessary to prepare an OHP original in advance. Therefore, no more original which has not been prepared cannot readily be projected on the screen to add any unscheduled explanation, for example, unless there is a copying or printing machine around.
To this end, a solution has been proposed in which an OHP is combined with a copying machine so that an original to be projected can be readily prepared by the copying machine. In this prior art apparatus, a support table is movably mounted on an apparatus body; during projecting, the support table is moved away from a focusing plate disposed on the top of the body, and the original on the focusing plate is illuminated by a lamp built in a projecting unit so that the light reflected on the focusing plate falls on the projecting unit.
With this prior arrangement, during projecting, when the retracted support table is moved to a position such as to cover the reflection-type focusing plate illuminated with light from the light source and remains in this position, the support table can be easily distorted or deformed.
Still during projecting, when the original cover on which the reflection-type focusing plate is plated is opened, the central axis of light of the focusing plate would deviate to cause the reflected light to strike on the eyes of the operator.